Some storage management systems (such as archiving systems and hierarchical storage management systems) may copy files from a primary storage device to a secondary storage device in order to conserve storage resources on the primary storage device. For example, an email archiving system may archive emails on a computing system that are more than a year old in order to free up storage space occupied by these emails on the computing system. Similarly, a hierarchical storage management system may copy files from a fast (but expensive) storage device to a cheaper (but slower) storage device in order to conserve storage resources on the more expensive storage device.
When a user or application attempts access to a file that has been moved to a secondary storage device by a storage management system, the storage management system may recall the file from the secondary storage device using one of three typical recall modes: 1) full recall (in which the complete file is downloaded from the secondary storage device and stored on the primary storage device), 2) partial recall (in which specific chunks of the file are downloaded from the secondary storage device to the primary storage device), and 3) pass-through recall (in which the file is downloaded and provided to a requesting application directly without storing the file on the primary storage device). Conventional storage management systems typically statically assign recall modes to volumes or devices. For example, a storage management system may specify that a particular storage device recall all files in full recall mode.
The static assignment of a recall mode to a volume or device may result in a number of problems and/or inefficiencies. For example, if a storage device attempts to perform multiple simultaneous recalls in full recall mode, then one or more of these recalls may fail if the storage and/or I/O capacity of the storage device is exceeded. Similarly, if a storage device attempts to recall a large file in partial recall mode, then completion of the recall operation may be unnecessarily delayed due to the large number of round trips that may be required to recall the various chunks of the file from the secondary storage device. In addition, if a storage device attempts to recall a file in pass-through recall mode multiple times within a short period of time, then disk I/O and/or network load may be unnecessarily increased.